This invention relates to DMA controllers and more particularly to DMA controllers used in controlling real-time data flow to analog signal acquisition and/or generation circuitry.
Data systems confront a variety of issues relating to data transfer in and out of memories including situations in which data may be lost. This is commonly handled by a direct memory access (DMA) controller. The data loss may occur in the situation in which the data needs to be correlated with other data. This may occur in an audio and video situation in which the audio needs to be timed properly with the video. In some of these situations the loss of the data may not be critical to the utility of the particular transmission that is occurring. It may degrade, in part, the value but perhaps only slightly depending upon the level of degradation. For example in a movie that is being transmitted as video and audio signals, a short term loss of the audio or video may have minimal or perhaps no effect on the enjoyment of the viewer. In many current systems a data loss may result in a required restart in order to reset timings and provide for the data in proper correlation. This can be a noticeably disruptive process.
Thus, there is a need for a DMA controller that reduces the need for restarting.